Carbon Dots for Single-Molecule Imaging of the Nucleolus

Carbon dots are newly discovered bright fluorescent biolabeling probes that nonspecifically bind to multiple cellular structures. Here we report yellow-orange emissive carbon dots that spontaneously localize inside the nucleolus of HeLa cells, specifically binding to the RNA. Single-particle measurements of carbon dots show fluorescence-intensity fluctuations with superior brightness and photostability. These optical properties were used for performing blinking-assisted localization microscopy that shows organization of the nucleolar RNA with improved resolution. Our study opens up the opportunity for single-molecule imaging and super-resolution microscopy applications using fluorescent carbon dots.